U.S. patent application number 13/499921 was filed with the patent office on 2012-08-30 for pressure sensitive adhesive comprising blend of synthetic rubber and functionalized synthetic rubber bonded to an acylic polymer.
Invention is credited to Vivek Bharti, Babu N. Gaddam, Guy D. Joly, Jingjing Ma, Sanat Mohanty, Shujun Wang, Peiwang Zhu.
Application Number | 20120216953 13/499921 |
Document ID | / |
Family ID | 43413891 |
Filed Date | 2012-08-30 |
United States Patent
Application |
20120216953 |
Kind Code |
A1 |
Bharti; Vivek ; et
al. |
August 30, 2012 |
PRESSURE SENSITIVE ADHESIVE COMPRISING BLEND OF SYNTHETIC RUBBER
AND FUNCTIONALIZED SYNTHETIC RUBBER BONDED TO AN ACYLIC POLYMER
Abstract
A pressure sensitive adhesive composition is described
comprising unfunctionalized (e.g. polyisobutylene) synthetic rubber
and an acrylic polymer having functionalized polyisobutylene
polymer bonded to the acrylic polymer. In some embodiments, the
functionalized polyisobutylene polymer has a first functional group
hydrogen bonded with a second functional group present in the
acrylic polymer backbone. In other embodiments, the functionalized
polyisobutylene polymer is covalently bonded to the acrylic polymer
backbone. Also described are adhesive articles, such as a tape,
methods of adhesively bonding, and methods of making a pressure
sensitive adhesive.
Inventors: |
Bharti; Vivek; (Cottage
Grove, MN) ; Wang; Shujun; (St. Paul, MN) ;
Joly; Guy D.; (Shoreview, MN) ; Gaddam; Babu N.;
(Woodbury, MN) ; Ma; Jingjing; (Cottage Grove,
MN) ; Mohanty; Sanat; (Woodbury, MN) ; Zhu;
Peiwang; (Woodbury, MN) |
Family ID: |
43413891 |
Appl. No.: |
13/499921 |
Filed: |
November 15, 2010 |
PCT Filed: |
November 15, 2010 |
PCT NO: |
PCT/US10/56646 |
371 Date: |
April 3, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61262611 |
Nov 19, 2009 |
|
|
|
Current U.S.
Class: |
156/332 ;
428/355EN; 524/522; 525/221 |
Current CPC
Class: |
C08L 2666/06 20130101;
C09J 121/00 20130101; C09J 123/22 20130101; C08F 290/042 20130101;
Y10T 428/2878 20150115; C08L 2666/08 20130101; C08L 23/26 20130101;
C09J 2421/00 20130101; C08L 51/06 20130101; C09J 7/243 20180101;
C09J 2423/00 20130101; C08L 55/005 20130101; C08L 23/22 20130101;
C08F 290/042 20130101; C08F 220/10 20130101; C09J 121/00 20130101;
C08L 2666/06 20130101; C09J 123/22 20130101; C08L 2666/08
20130101 |
Class at
Publication: |
156/332 ;
428/355.EN; 525/221; 524/522 |
International
Class: |
C09J 119/00 20060101
C09J119/00; C09J 133/02 20060101 C09J133/02; B32B 37/12 20060101
B32B037/12; C09J 7/02 20060101 C09J007/02 |
Claims
1. A pressure sensitive adhesive composition comprising:
unfunctionalized synthetic rubber; and an acrylic polymer having
functionalized polyisobutylene polymer bonded to the acrylic
polymer.
2. The pressure sensitive adhesive of claim 1 wherein the
functionalized polyisobutylene polymer has a first functional group
hydrogen bonded with a second functional group present in the
acrylic polymer backbone.
3. The pressure sensitive adhesive composition of claim 2 wherein
the first or second functional group is a hydrogen bond acceptor
and the other functional group is a hydrogen bond donor.
4. The pressure sensitive adhesive of claim 1 wherein the
functionalized polyisobutylene polymer is covalently bonded to the
acrylic polymer backbone.
5. The pressure sensitive adhesive composition of claim 4 wherein
the functionalized polyisobutylene polymer covalently bonded to the
acrylic polymer backbone is prepared from polymerizing
(meth)acrylate-functionalized PIB and alkyl (meth)acrylate
monomers.
6. The pressure sensitive adhesive composition of claim 1 wherein
the unfunctionalized synthetic rubber comprises
polyisobutylene.
7. The pressure sensitive adhesive composition of claim 1 wherein
the functionalized polyisobutylene has a number average molecular
weight of less than 10,000 g/mole.
8. The pressure sensitive adhesive composition of claim 1 wherein
the unfunctionalized synthetic rubber has a weight average
molecular weight ranging from about 75,000 g/mole to 4,000,000
g/mole.
9. The pressure sensitive adhesive composition of claim 1 wherein
the acrylic polymer is a copolymer of at least one
alkyl(meth)acrylate and at least one carboxylic acid.
10. The pressure sensitive adhesive composition of claim 9 wherein
the alkyl (meth)acrylate is a C4 to C20 alkyl (meth)acrylate.
11. The pressure sensitive adhesive composition of claim 9 wherein
the alkyl (meth)acrylate is a C4 to C8 alkyl (meth)acrylate.
12. The pressure sensitive adhesive composition of claim 2 wherein
the adhesive composition further comprises a chemical crosslinker
that covalently crosslinks the functional groups.
13. The pressure sensitive adhesive composition of claim 12 wherein
the crosslinker is selected from an aziridine crosslinker.
14. The pressure sensitive adhesive composition of claim 1 wherein
the composition comprises an unfunctionalized polyisobutylene
having a number average molecular weight of less than 10,000
g/mole.
15. The pressure sensitive adhesive composition of claim 1 further
comprising a tackifying resin, a plasticizer, or a mixture
thereof.
16. An article comprising: a substrate; and the pressure sensitive
adhesive of claim 1 coated on at least one surface of the
substrate.
17. The article of claim 16 wherein the articles is a tape.
18. A method of bonding comprising: providing a substrate; applying
the pressure sensitive adhesive of any of claim 1 on a surface of
the substrate; and contacting the pressure sensitive adhesive with
another substrate.
19. The method of claim 18 wherein at least one substrate has a
surface energy of less than 37 dynes/cm.
20. A method of making a pressure sensitive adhesive comprising
blending: an unfuntionalized synthetic rubber; and an acrylic
polymer having functionalized polyisobutylene polymer bonded to the
acrylic polymer.
Description
BACKGROUND
[0001] Pressure sensitive adhesives (PSAs) are an important class
of materials. In recent years, there has been a significant
increase in the use of plastics, vulcanized rubbers, and
thermoplastic vulcanizates ("TPV") in the automotive, appliance and
electronics markets. Generally, these materials combine the
desirable characteristics of vulcanized rubber with the processing
ease of thermoplastics. However, bonding to these and other low
surface energy substrates currently requires priming the substrate
surface prior to bonding with a pressure sensitive adhesive
("PSA"). The priming process can be expensive and labor intensive,
and may present environmental concerns.
[0002] Accordingly, industry would find advantage in new pressure
sensitive adhesives that can exhibit good adhesion to a variety of
substrates, such as low surface energy substrates.
SUMMARY
[0003] In one embodiment, a pressure sensitive adhesive composition
is described comprising unfunctionalized (e.g. polyisobutylene)
synthetic rubber and an acrylic polymer having functionalized
polyisobutylene polymer bonded to the acrylic polymer. In some
embodiments, the functionalized polyisobutylene polymer has a first
functional group hydrogen bonded with a second functional group
present in the acrylic polymer backbone. In other embodiments, the
functionalized polyisobutylene polymer is covalently bonded to the
acrylic polymer backbone.
[0004] In another embodiment, a pressure sensitive adhesive coated
article is described, such as a tape. The article comprises a
substrate and the pressure sensitive adhesive describe herein
coated on at least one surface of the substrate.
[0005] In another embodiment, a method of bonding is described
comprising providing a substrate, applying the pressure sensitive
adhesive described herein on a surface of the substrate, and
contacting the pressure sensitive adhesive with another
substrate.
[0006] In another embodiment, a method of making a pressure
sensitive adhesive is described. The method comprises blending an
unfunctionalized synthetic rubber and an acrylic polymer having
functionalized polyisobutylene polymer bonded to the acrylic
polymer.
[0007] In each of these embodiments, the functionalized
polyisobutylene is typically a relatively low molecular weight
liquid polymer, having a number average molecular weight of less
than 10,000 g/mole. The unfunctionalized (e.g. PIB) synthetic
rubber is typically a relatively high molecular weight polymer,
having a weight average molecular weight ranging from about 75,000
g/mole to 4,000,000 g/mole.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a microscopic (10.times.) image of a blend of
unfunctionalized polyisobutylene totaling 50 wt-% and 50 wt-%
acrylic polymer.
[0009] FIG. 2 is a microscopic (10.times.) image of a blend of
functionalized and unfunctionalized polyisobutylene totaling 50
wt-% and 50 wt-% acrylic polymer.
[0010] FIG. 3 is a microscopic (20.times.) image of a blend of
functionalized and unfunctionalized polyisobutylene totaling 75
wt-% and 25 wt-% acrylic polymer.
[0011] FIG. 4 is a microscopic (20.times.) image of a blend of
functionalized and unfunctionalized polyisobutylene totaling 50
wt-% and 50 wt-% acrylic polymer.
[0012] FIG. 5 is a microscopic (20.times.) image of a blend of
functionalized and unfunctionalized polyisobutylene totaling 25
wt-% and 75 wt-% acrylic polymer.
DETAILED DESCRIPTION
[0013] As used in the art, the term "pressure-sensitive adhesive"
refers to adhesive compositions that have (1) aggressive and
persistent tack, (2) adherence with no more than finger pressure,
(3) sufficient ability to hold onto an adherend, and (4) sufficient
cohesive strength to be cleanly removable from the adherend.
[0014] The pressure sensitive adhesive composition described herein
comprises at least one polyisobutylene having a first functional
group, also referred to herein as the "functionalized
polyisobutylene". The functional group of the functionalized
polyisobutylene is typically a (e.g. terminal) group that can
hydrogen bond or covalently bond to (e.g. pendant carboxylic acid
groups of) of backbone of an acrylic polymer or a functional group
appended to the (e.g. backbone) of the acrylic polymer.
[0015] In some embodiments, the functionalized polyisobutylene is a
functionalized homopolymer of isobutylene. In other embodiments,
the functionalized polyisobutylene is a copolymer comprising
isobutylene repeat units and a small amount of units derived from
another monomer such as, for example, styrene, isoprene, butene, or
butadiene. These copolymers are typically prepared from a monomer
mixture that includes at least 70 weight percent, at least 75
weight percent, at least 80 weight percent, at least 85 weight
percent, at least 90 weight percent, or at least 95 weight percent
isobutylene based on the weight of monomers in the monomer mixture.
Typically, at least 70 weight percent, at least 75 weight percent,
at least 80 weight percent, at least 85 weight percent, or at least
90 weight percent of the polyisobutylene copolymer is formed from
isobutylene repeat units. Exemplary copolymers include isobutylene
copolymerized with isoprene.
[0016] The functionalized polyisobutylene is typically a liquid
polymer having a relatively low to intermediate number average
(M.sub.n) molecular weight. The M.sub.n is typically at least 500
g/mole, 750 g/mole, or about 1,000 g/mole. In some embodiments, the
M.sub.n of the functionalized polyisobutylene is no greater than
25,000 g/mole, or 10,000 g/mole, or 5,000 g/mole.
[0017] The functionalized polyisobutylene typically has a glass
transition temperature of no greater than about -30.degree. C. or
less, no greater than about -50.degree. C., or no greater than
about -70.degree. C., as determined by differential scanning
calorimetry (DSC).
[0018] The functional group of the functionalized PIB can be any
functional group that forms a hydrogen bond or covalent bond with
(e.g. pendant carboxylic acid groups of) the backbone of an acrylic
polymer or a functional group appended to the (e.g. backbone) of
the acrylic polymer.
[0019] In some embodiments, the first functional group and second
functional group form a hydrogen bond. In this embodiment, the
predominant bond between the functional group of the
polyisobutylene and the acrylic polymer is a hydrogen bond. Hence,
in this embodiment, such functional groups do not form a covalent
bond. A hydrogen bond is an attractive force, or bridge, occurring
in polar compounds in which a hydrogen atom of one molecule or
functional group is attracted to unshared electrons of another. The
hydrogen atom is the positive end of one polar molecule or
functional group (otherwise known as a hydrogen bond donor) and
forms a linkage with the electronegative end of another molecule or
functional group (otherwise known as a hydrogen bond acceptor).
Functional groups that have non-polar covalent bonds do not form
hydrogen bonds.
[0020] Common hydrogen-bond donors include carboxylic acids,
phosphonic acids, phosphoric acid esters, sulfonic acids, sulfuric
acids, alcohols, and phenols.
[0021] Common hydrogen-bond acceptors include nitrogen containing
groups such as amines, amides, imines, imides, nitriles and ureas
as well as aromatic nitrogen-based functional groups such as
pyridines, imidazoles, etc. Other hydrogen-bond acceptors include
carboxylate groups (carboxylic acid, carboxylic ester),
phosphonates, sulfoxides, sulfones, and carbamates.
[0022] In one embodiment, the acrylic polymer has carboxylic acid
functionality and the functionalized PIB has a functional (e.g.
terminal) group that hydrogen bonds with the carboxylic acid group
of the acrylic polymer. In this embodiment, the functional group of
the functionalized PIB is not acrylate, methacrylate, or any other
functional group that covalently bonds with a (meth)acrylate group
via free radical polymerization. This approach can be preferred
since it can utilize commercially available functionalized PIB
having a terminal nitrogen-containing group such as an amine or
imide.
[0023] Various functionalized PIB materials are commercially
available. For example, polyisobutyleneamine having a number
average molecular weight(M.sub.n) of about 1,000 grams/mole and a
molar mass distribution M.sub.w/M.sub.n=1.6) is commercially
available from BASF Corporation (Florham Park, N.J.) under the
trade designation "Kerocom.RTM. PIBA03". Further, polyisobutene
succinimide is available from BASF under the trade designation
"Kerocom.RTM. PIBSI". An anhydride-terminated polyisobutylene
(M.sub.n) of about 1,000 grams/mole) is available from BASF under
the trade designation "Glissopal SA".
[0024] The commercially available functionalized PIB materials are
suitable for the formation of hydrogen bonds wherein the carboxylic
acid group is the proton donor (i.e. H-bond donor) and the
nitrogen-containing group (i.e. amine or imide) is the proton
acceptor (i.e. H-bond acceptor).
[0025] However, it is appreciated that the functional groups can be
reversed. For example, the functionalized PIB may have a (e.g.
terminal) carboxylic acid group, provided that the carboxylic acid
groups of the acrylic polymer are pre-reacted to convert these
groups to a functional group that will then in turn form a hydrogen
bond with the carboxylic acid groups of the PIB.
[0026] For example, polyisobutyleneamine (e.g. Kerocom.RTM. PIBA03)
could be reacted with an anhydride (such as succinic anhydride or
glutaric anhydride) to provide a carboxylic acid-functionalized PIB
material. A carboxylic acid-functionalized PIB could also be
prepared by reaction of anhydride-terminated polyisobutylene (e.g.
Glissopal SA) with an alcohol (such as 1-octanol) to provide a PIB
chain terminated with an ester and a carboxylic acid.
[0027] Amine-functionalized acrylic polymers can be prepared by
copolymerization of at least one amino comonomer with alkyl
(meth)acrylate monomers. Suitable amino comonomers are olefinically
unsaturated, polymerizable compounds that contain at least one
primary or secondary amino group, e.g. amino methacrylates such as
tert-butylaminoethyl methacrylate or
meta-isopropenyl-.alpha.,.alpha.-dimethylbenzylamine. Amino groups
can also be obtained by the reaction of acid polymers with
aziridines such as ethylene imine as well as other techniques known
for adding amine functionality to polymers.
[0028] Various amino comomomers are known including for example
N,N-dimethylaminopropyl methacrylamide (DMAPMAm);
N,N-diethylaminopropyl methacrylamide (DEAPMAm);
N,N-dimethylaminoethyl acrylate (DMAEA); N,N-diethylaminoethyl
acrylate (DEAEA); N,N-dimethylaminopropyl acrylate (DMAPA);
N,N-diethylaminopropyl acrylate (DEAPA); N,N-dimethylaminoethyl
methacrylate (DMAEMA); N,N-diethylaminoethyl methacrylate (DEAEMA);
N,N-dimethylaminoethyl acrylamide (DMAEAm); N,N-dimethylaminoethyl
methacrylamide (DMAEMAm); N,N-diethylaminoethyl acrylamide
(DEAEAm); N,N-diethylaminoethyl methacrylamide (DEAEMAm);
N,N-dimethylaminoethyl vinyl ether (DMAEVE); N,N-diethylaminoethyl
vinyl ether (DEAEVE); and mixtures thereof Other useful basic
monomers include vinylpyridine, vinylimidazole, tertiary
amino-functionalized styrene (e.g., 4-(N,N-dimethylamino)-styrene
(DMAS), 4-(N,N-dimethylamino)-styrene (DEAS)), and mixtures
thereof.
[0029] Other functionalized polyisobutylene can be prepared by
various methods as known in the art. For example,
hydroxy-functionalized PIBs could also be synthesized by reacting
anhydride-terminated polyisobutylene (e.g. Glissopal SA) with amino
alcohols or diols, or by reacting poly-isobutyleneamine (e.g.
Kerocom PIBA03) with 2-chloroethanol or epoxides.
Pyridine-functionalized PIB-based materials can be synthesized by
reacting an amino or hydroxy-bearing pyridine compound with a
polyisobutylene (e.g. succinic) anhydride (e.g. Glissopal.RTM. SA).
Alternatively, poly-isobutyleneamine (e.g. Kerocom.RTM. PIBA03) can
be reacted with 3-(chloromethyl)pyridine to provide a
pyridyl-substituted PIB derivative. Carbamate-functionalized PIB
could be obtained by reacting poly-isobutyleneamine (e.g.
Kerocom.RTM. PIBA03) with isocyanate electrophiles.
[0030] Alternatively, the first functional group of the
functionalized PIB and second functional group of the acrylic
polymer form a covalent bond. In this embodiment, the first
functional group of the functionalized PIB can be any functional
group that forms a covalent bond with the backbone of an acrylic
polymer. Alternatively, the first functional group of the
functionalized PIB is a polymerizable (meth)acrylate functionality
that can be copolymerized with typical alkyl (meth)acrylate
monomers.
[0031] Many common functional groups can be used to form covalent
bonds between the PIB material and acrylic polymer. For example,
amine- or alcohol-functionalized PIB materials could be reacted
with (meth)acrylate polymers that comprise activated ester-type
functional groups. Such activated esters include anhydrides,
N-hydroxysuccinimide esters, pentafluorophenyl esters, and acid
chlorides. For example, an acrylate polymer containing
N-hydroxysuccinimide ester functional groups can be prepared by
using acrylic acid N-hydroxysuccinimide ester as an acrylate
monomer. Alternatively, carboxylic acid residues in the
(meth)acrylate polymer could be converted to activated esters by
common methods known to those skilled in the art. Another route to
making covalently bonded PIB-acrylate materials would be to react
amine- or alcohol-functionalized PIB materials with (meth)acrylate
polymers that contained azlactone rings. (Meth)acrylate polymers
that bear azlactone rings can be prepared by using
2-vinyl-4,4-dimethyl-5-oxazolone as a comonomer. A suitable
amine-functionalized PIB material is Kerocom.RTM. PIBA03.
[0032] Yet another strategy to make covalently bonded
PIB-(meth)acrylate materials is to react amine- or
hydroxy-functionalized PIB-materials with an
isocyanate-functionalized (meth)acrylate polymer. Such
(meth)acrylate polymers can be prepared by using 2-isocyanatoethyl
methacrylate as a comonomer.
[0033] It is also possible to reverse the first and second reacting
functional groups. For example, amine- or hydroxy-functionalized
(meth)acrylate polymers can be reacted with a PIB polymer that is
functionalized with an activated ester. Amine-functionalized
(meth)acrylate polymers can be prepared by using an
amine-functionalized (meth)acrylate monomer (see above) as a
comonomer. Alcohol-functionalized (meth)acrylate polymers can be
prepared, for example, by using 2-hydroxyethyl acrylate or
2-hydroxyethyl methacrylate as a comonomer in the preparation of
the (meth)acrylate polymer. A suitable reaction partner for amine-
or alcohol-functionalized (meth)acrylate polymers would be an
anhydride-functionalized PIB material such as Glissopal.RTM.
SA.
[0034] Methacrylate- and acrylate-functionalized PIB can be
synthesized as known in the art. See for example WO2008/066914,U.S.
Pat. No. 5,171,760, and "Sytheses and Characterization of
Polyisobutylene Macromonomer with Methacrylate, Acrylate, Glycidyl
Ether, or Vinyl Ether End-Functionality", (Macromolecules 2009, 42,
3958-3964). Further, U.S. Pat. No. 5,665,823 and U.S. Pat. No.
6,0554,549 describe PIB-based materials having a silanol end group
that can be used to make acrylate-functionalized PIB polymers that
have a siloxane linkage between the PIB chain and the acrylate
functionality.
[0035] The presence and concentration of functional groups within a
functionalized PIB material can be determined by Proton Nuclear
Magnetic Resonance. Typically, the functionalized PIB material
comprises at least 3 mol-% of functional groups. The concentration
of functional groups is generally no greater than 10 mol-%.
[0036] The amount of functionalized PIB material in the pressure
sensitive adhesive composition can vary depending on the desired
end use of the adhesive composition. Typically, however, the
concentration of functionalized PIB material is at least 2 wt-%, or
5 wt-%, or 10 wt-% in order to improve adhesion with low surface
energy substrates such as those prepared from polyolefins. The
concentration of functionalized PIB material is typically no
greater than 40 wt-%. Particularly when the pressure sensitive
adhesive composition is also intended for use with higher surface
energy substrates, the concentration of functionalized PIB material
is typically 5 wt-% to 30 wt-%, when utilizing a functionalized PIB
material having a relatively low molecular weight (e.g. M.sub.n
less than 10,000 g/mole).
[0037] With reference to FIGS. 1-2, the functionalized PIB material
is surmised to compatibilize the relatively high molecular weight
PIB material with the acrylic polymer material. The weight ratio of
functionalized PIB material to unfunctionalized (e.g. PIB)
synthetic rubber material can range from about 1:1 to about
1:3.
[0038] The pressure sensitive adhesive composition described herein
further comprises at least one acrylic polymer. The acrylic polymer
generally comprises the reaction product of at least one alkyl
(meth)acrylate and at least one comonomer, most commonly a
carboxylic acid, that provides functional groups along the backbone
of the acrylic polymer. In some embodiments, the acrylic copolymer
of the adhesive composition comprises at least about 70 wt-%, in
some embodiments, at least about 80 wt-%, at least about 90 wt-%,
at least about 95 wt-%, or even about 98 wt-% of at least one alkyl
(meth)acrylate.
[0039] In some embodiments, the alkyl (meth)acrylate contains 4 to
20 carbon atoms, e.g., 4 to 8 carbon atoms. Exemplary alkyl
(meth)acrylates include isooctyl acrylate (IOA), 2-octyl acrylate
(2-OA), 2-ethylhexyl acrylate (2-EHA), butyl acrylate (BA),
isobornyl acrylate (IBA), and combinations thereof. In some
embodiments, the acrylic copolymer utilized in the PSA comprises at
least two of such alkyl (meth)acrylates, such as isooctyl acrylate
and isobornyl acrylate.
[0040] In some embodiments, acrylic adhesive composition comprises
no greater than 10 parts of comonomer, such as carboxylic acid.
Since, in some embodiments, the comonomer provides the functional
groups that compliment the functionality of the PIB, the
concentration of comonomer is typically at least 0.5, 1, 2, 3, 4,
or 5 wt-%. Exemplary comonomers include carboxylic acids such as
acrylic acid or methacrylic acid. In some embodiments, a comonomer
(e.g. (meth)acrylate acid) concentration of 5 wt-% to 10 wt-% or 15
wt-% provides increased cohesive strength, as evident by the shear
values.
[0041] The amount of acrylic polymer in the pressure sensitive
adhesive composition can vary depending on the desired end use of
the adhesive composition. Typically, however, the concentration of
acrylic polymer is at least 20 wt-% or 25-wt-%. The concentration
of acrylic polymer may range up to 75 wt-% or 80 wt-%. Particularly
when the pressure sensitive adhesive composition is also intended
for use with both low and higher surface energy substrates, the
concentration of acrylic polymer typically ranges from 30 wt-% to
70 wt-%, 35 wt-% to 65 wt-%, or 40 wt-% to 60 wt-%. With reference
to FIGS. 3-5, as the weight ratio of acrylic polymer to total PIB
polymer (i.e. the total amount of both functionalized and
unfunctionalized PIB approaches 1:1, the blend can have a
bicontinuous phase morphology (i.e. a semi-interpenetrating
network).
[0042] In some embodiments, the alkyl (meth)acrylate monomer(s) and
functionalizing comonomer(s) are prepolymerized into an acrylic
polymer and then combined with the functionalized PIB.
[0043] In other embodiments, the alkyl (meth)acrylate monomer(s)
and functionalizing comonomer(s) are combined with the
functionalized PIB and then the monomers are polymerized. The alkyl
(meth)acrylate monomers and functionalized PIB can be polymerized
by use of a thermal initiator or photoinitiator. The thermal
initiator is often a peroxide, hydroperoxide, or azo compound.
Alternatively, the alkyl(meth)acrylate monomers can be polymerized
using ultraviolet radiation by use of an alpha-cleavage type
photoinitiator including but not limited to benzoin or benzoin
alkyl ethers. Either method of preparation results in a composition
comprising a blend of functionalized PIB and acrylic polymer
wherein the functionalized PIB is hydrogen- or covalently bonded to
the functional groups along the backbone of the acrylic
polymer.
[0044] For embodiments wherein the alkyl (meth)acrylate monomer(s)
and functionalizing comonomer(s) are prepolymerized into an acrylic
polymer and then combined with the functionalized PIB, the reaction
product of the functionalized PIB and the acrylic polymer can be
represented as follows, wherein Z represents a hydrogen-bond or
covalent bond between complimentary functional groups:
##STR00001##
[0045] In some embodiments, the adhesive may comprise solely the
functionalized PIB hydrogen- or covalently bonded to the acrylic
polymer and the unfunctionalized (e.g. PIB) synthetic rubber, in
the absence of crosslinker or any other optional components.
[0046] In other embodiments, the adhesives of the present
disclosure may be crosslinked to improve their mechanical
properties. In many embodiments, chemical crosslinking is preferred
to improve the cohesive strength (as indicated by the static shear)
of the pressure sensitive adhesive. For example, the adhesive may
comprise a chemical crosslinker that is suitable for crosslinking
the (e.g. carboxylic acid) functional groups of the acrylic polymer
with each other or functional groups of the acrylic polymer with
functional groups of the functionalized PIB. Suitable crosslinkers
are known in the art such as aziridine or bisaziridine
crosslinkers. One suitable bisaziridine crosslinker is prepared as
described in U.S. Provisional Application No. 61/158,485, filed
Mar. 9, 2009 (Peiwang Zhu et al. AZIRIDINE CROSSLINKING AGENTS FOR
ACRYLIC ADHESIVES).
[0047] When the pressure sensitive adhesive (e.g. precursor)
further comprises a chemical crosslinker, the reaction product of
the functionalized PIB and the acrylic polymer can be represented
as follows:
##STR00002##
[0048] When present, the concentration of chemical crosslinker in
the pressure sensitive adhesive composition is typically at least
0.025 wt-% and no greater than 2 wt-%.
[0049] The adhesive further comprises at least one unfunctionalized
(e.g. PIB) synthetic rubber material. The unfunctionalized (e.g.
PIB) synthetic rubber material typically has substantially higher
molecular weight than the functionalized (e.g. PIB) synthetic
rubber material. In some embodiments, the weight average molecular
weight (M.sub.w) of the unfunctionalized (e.g. PIB) synthetic
rubber material is at least 75,000 grams per mole, at least 100,000
grams per mole, at least 250,000 grams per mole, at least 500,000
grams per mole, or even at least 1,000,000 grams per mole. The
weight average molecular weight is typically no greater than
4,000,000 g/mole.
[0050] The unfunctionalized (e.g. PIB) synthetic rubber material
can be a homopolymer, copolymer, or a mixture thereof. Copolymers
can be random or block copolymers. Block copolymers can include the
polyisobutylene sections in the main backbone, in a side chain, or
in both the main backbone and a side chain of the polymeric
material. The polyisobutylene material is typically prepared by
polymerizing isobutylene alone or by polymerizing isobutylene plus
additional ethylenically unsaturated monomers in the presence of a
Lewis Acid- catalyst such as aluminum chloride, boron trichloride
(with titanium tetrachloride as a cocatalyst), or boron
trifluoride.
[0051] Unfunctionalized polyisobutylene materials are commercially
available from several manufacturers. Homopolymers are commercially
available, for example, under the trade designation OPPANOL (e.g.,
OPPANOL B10, B15, B30, B50, B100, B150, and B200) from BASF Corp.
(Florham Park, N.J.). These polymers often have a weight average
molecular weight (M.sub.w) in the range of about 40,000 to
4,000,000 grams per mole. Still other exemplary homopolymers are
commercially available from United Chemical Products (UCP) of St.
Petersburg, Russia in a wide range of molecular weights. For
example, homopolymers commercially available from UCP under the
trade designation SDG have a viscosity average molecular weight
(M.sub.v) in the range of about 35,000 to 65,000 grams per mole.
Homopolymers commercially available from UCP under the trade
designation EFROLEN have a viscosity average molecular weight
(M.sub.v) in the range of about 480,000 to about 4,000,000 grams
per mole. Homopolymers commercially available from UCP under the
trade designation JHY have a viscosity average molecular weight in
the range of about 3000 to about 55,000 grams per mole. These
homopolymers typically do not have reactive double bonds. It is
appreciated that the unfunctionalized (e.g. PIB) synthetic rubber
may have a very small concentration of reactive double bonds or
other functional groups that are residual to the polymerization
thereof The concentration of such reactive double bonds or other
functional groups is typically less than 5, 4, 3, or 2 mol %. Such
olefinic unsaturations are generally non-polar and thus not
suitable functional groups for the formation of hydrogen bonds.
Such olefinic unsaturations are also typically not suitable
functional groups for formation of covalent bonds via free-radical
polymerization.
[0052] The concentration of unfunctionalized (e.g. PIB) synthetic
rubber material in the pressure sensitive adhesive composition is
typically at least 5 wt-%, 10 wt-%, or 15 wt-% and no greater than
40 wt-% or 50 wt-%. In some embodiments, the concentration range of
the unfunctionalized (e.g. PIB) synthetic rubber is based on the
unfunctionalized (e.g. PIB) synthetic rubber having a molecular
weight of about 500,000 g/mole.
[0053] In some embodiments, the adhesive comprises the
functionalized (e.g. PIB) synthetic rubber hydrogen or covalently
bonded to the acrylic polymer, crosslinker, and both a high
molecular weight unfunctionalized (e.g. PIB) synthetic rubber and
low molecular weight unfunctionalized (e.g. PIB) synthetic rubber.
The low molecular weight (e.g. PIB) synthetic rubber materials are
liquids at room temperature and can function as a plasticizer with
a variety of elastomeric materials. Generally, such polyisobutylene
materials have a number average molecular weight of no greater than
10,000 g/mole, e.g., no greater than 5,000 g/mole, or even no
greater than 2,000 g/mole. The number average molecular weight is
typically at least about 500 g/mole or 1000 g/mole. The ratio of
the weight average molecular weight to the number average molecular
weight is typically in the range of about 1.6 to 2.0.
[0054] Exemplary low molecular weight polyisobutylene homopolymers
are commercially available under the trade designation GLISSOPAL
(e.g., GLISSOPAL 1000, 1300, and 2300) from BASF Corp. (Florham
Park, N.J.). These polyisobutylene materials usually have terminal
double bonds and are considered to be reactive polyisobutylene
materials.
[0055] When present, the concentration of unfunctionalized low
molecular weight polyisobutylene (e.g. PIB) material in the
pressure sensitive adhesive composition is typically at least 5
wt-%, 10 wt-%, or 20 wt-% and no greater than 30 wt-%.
[0056] In some embodiments, the adhesive may comprise the
functionalized (e.g. PIB) synthetic rubber hydrogen bonded to the
acrylic polymer, crosslinker, unfunctionalized high molecular
weight (e.g. PIB) synthetic rubber materials, in the absence of any
tackifier(s) or plasticizer(s). In other embodiments, the adhesive
comprises at least one tackifier(s), plasticizer(s), or mixtures
thereof.
[0057] The tackifier can have any suitable softening temperature or
softening point. The softening temperature is often less than
200.degree. C., less than 180.degree. C., less than 160.degree. C.,
less than 150.degree. C., less than 125.degree. C., or less than
120.degree. C. In applications that tend to generate heat, however,
the tackifier is often selected to have a softening point of at
least 75.degree. C. Such a softening point helps minimize
separation of the tackifier from the rest of the adhesive
composition when the adhesive composition is subjected to heat such
as from an electronic device or component. The softening
temperature is often selected to be at least 80.degree. C., at
least 85.degree. C., at least 90.degree. C., or at least 95.degree.
C. In applications that do not generate heat, however, the
tackifier can have a softening point less than 75.degree. C.
[0058] Exemplary tackifiers include hydrocarbon resins and
hydrogenated hydrocarbon resins, e.g., hydrogenated cycloaliphatic
resins, hydrogenated aromatic resins, or combinations thereof.
Suitable tackifiers are commercially available and include, e.g.,
those available under the trade designation ARKON (e.g., ARKON P or
ARKON M) from Arakawa Chemical Industries Co., Ltd. (Osaka, Japan);
those available under the trade designation ESCOREZ (e.g., ESCOREZ
1315, 1310LC, 1304, 5300, 5320, 5340, 5380, 5400, 5415, 5600, 5615,
5637, and 5690) from Exxon Mobil Corporation, Houston, Tex.; and
those available under the trade designation REGALREZ (e.g.,
REGALREZ 1085, 1094, 1126, 1139, 3102, and 6108) from Eastman
Chemical, Kingsport, Tenn.
[0059] The concentration of tackifier can vary depending on the
intended adhesive composition. In some embodiments, the amount of
tackifier is at least 10 wt-% or 20 wt-%. The maximum amount of
tackifier is typically no greater than 40 wt-%, 50 wt-%, or 60
wt-%.
[0060] Other optional additives can include, for example,
initiators, ultraviolet absorbents (e.g., benzotriazole, oxazolic
acid amide, benzophenone, or derivatives thereof), ultraviolet
stabilizers (e.g., hindered amines or derivatives thereof,
imidazole or derivatives thereof, phosphorous-based stabilizers,
and sulfur ester-based stabilizers), antioxidants (e.g., hindered
phenol compounds, phosphoric esters, or derivatives thereof).
Exemplary antioxidants include those available from Ciba Specialty
Chemicals Incorporated, Tarrytown, N.Y.
[0061] The adhesives of the present disclosure may be combined with
a substrate to form any number of typical adhesive articles, e.g.,
single- and double-coated tapes, and laminating adhesives.
Generally, laminating adhesives may comprise either a free film of
adhesive or an adhesive film embedded with a support, e.g., a woven
or non-woven scrim.
[0062] Such products can be formed by applying (e.g., coating,
casting, or extruding) the adhesive onto a release liner, and
drying and/or curing the adhesive.
[0063] The adhesives of the present disclosure may also be applied
to one or both sides of a substrate to form a single- or
double-coated tape. Any know substrate, including single and
multi-layer substrates comprising one or more of paper, polymeric
film, and metal (e.g., metal foil) may be used. In some
embodiments, one or more layers of the substrate may be foam. In
some embodiments, one or both adhesive layers may be bonded
directly to the substrate. In some embodiments, one or both
adhesive layers may be indirectly bonded to the substrate. For
example, in some embodiments, one or more intermediate layers
(e.g., primer layers) may be interposed between the substrate and
the adhesive layer.
[0064] The adhesive is useful for bonding to a variety of metal and
polymeric materials. Metals typically have a surface energy of at
least about 500 dynes/cm. For example stainless steel is reported
to have a surface energy of about 700-1100 dynes/cm. Inorganic
oxides generally have a surface energy less than that of metals.
For example, glass is reported to have a surface energy of about
250-500 dynes/cm. The adhesive is particularly useful for bonding
to various polymeric materials. Polymeric materials such as
plastics generally have a surface energy of less than 100 dynes/cm,
75 dynes/cm, or 50 dynes/cm. For example, polyester is reported to
have surface energy of 43 dynes/cm; polycarbonate 42 dynes/cm;
polyvinyl chloride 39 dynes/cm; and acrylic 38 dynes/cm. Even lower
surface energy materials have a surface energy of less than 37
dynes/cm. These include for example polyvinyl acetate, polystyrene,
acetal, ethylene vinyl acetate, and polyethylene reported to have a
surface energy of 31 dynes/cm.
[0065] The pressure sensitive adhesive can exhibit various peel and
shear properties, depending on the intended end use.
[0066] In some embodiments the 90 degree peel to glass, stainless
steel, high density polyethylene (HDPE), polypropylene (PP), or
EPDM is at least 5 oz/inch (5 N/dm) for a temporary removable or
low temperature PSA. For masking tapes, the 90 degree peel to
glass, stainless steel, HDPE, PP, or EPDM is typically 15-20
oz/inch (16-22 N/dm). In other embodiments the 90 degree peel to
glass, stainless steel, HDPE, or PP is at least 50, 60, 70, 80 or
90 oz/inch (55, 66, 77, 88 or 99 N/dm). In at least some
embodiments, the shear at room temperature (23.degree. C.) is at
least 300 minutes, 500 minutes, or 800 minutes. In some favored
embodiments, the adhesive exhibits good adhesion to both high and
low surface energy substrates. In such embodiments, the 90 degree
peel to glass or stainless steel is at least 50, 60, 70, 80 or 90
oz/inch (55, 66, 77, 88 or 99 N/dm) in combination with the 90
degree peel to PP being at least 30, 40, 50, or 60 oz/inch.
Further, the 90 degree peel to EPDM is typically at least 30, 40,
or 50 oz/inch; whereas the 90 degree peel to HDPP is at least 30,
40, or 50 oz/inch. In some favored embodiment, the shear at room
temperature (23.degree. C.) or 70.degree. C. is at least 2,000
minutes; 4,000 minutes; 8,000 minutes; or 10,000 minutes.
[0067] The following, non-limiting, examples further describe
exemplary adhesives and adhesive articles of the present
disclosure, as well as exemplary methods for making such adhesives
and adhesive articles. All percents are by weight unless otherwise
indicated.
[0068] Test Methods:
[0069] 90.degree. Angle Peel Adhesion Strength Test. Evaluation of
peel adhesion strength at an angle of 90.degree. was performed as
described in the ASTM International standard, D3330, Method F, with
a 1.3 cm.times.20 cm (1/2 in..times.8 in.) test specimen using an
IMASS SP-200 slip/peel tester (available from IMASS, Inc., Accord,
Mass.) at a peel rate of 305 mm/minute (12 inches/minute). The
samples were adhered to the test panels by rolling down the tapes
with a 2.0 kg (4.5 lb.) rubber roller using 4 passes. The test
panels included:
TABLE-US-00001 Material Description Source EPDM
Ethylene/propylene-diene class M rubber; Zatkoff Seals & having
a durometer hardness of 60, Packings, measuring 5.1 .times. 12.7
.times. 0.15 cm Warren, MI (2 .times. 5 .times. 0.059 in.);
available as EPDM, Part No. RZW07-015 PP Polypropylene (0.91 g/cc)
(Quadrant EPP Proteus Natural Homopolymer Polypropylene); Stainless
SS, 304, 18 gauge stainless steel, bright ChemInstruments, Steel
annealed finish. Incorported, Fairfield, OH HDPE 2'' .times. 5'',
0.2'' thick, 0.96 g/cc high density obtained from polyethylene
(Quadrant EPP HDPE) Aeromat Plastics Inc., Burnsville, MN Glass 6''
.times. 6'', 1/4'' float glass
[0070] The test panels were cleaned with a 1:1 isopropyl alcohol/
water mixture and thoroughly dried prior to use. The peel tests
were performed after a 15 min dwell time in a controlled
environment room on the test panel, unless otherwise stated. The
average peel adhesion force required to remove the tape from the
panel was measured in ounces and is expressed in Oz/inch, based on
2 test samples.
[0071] Static Shear Strength at 23.degree. C./50% Relative
Humidity: Evaluation of static shear strength was performed as
described in the ASTM International standard, D3654, Procedure A,
with a 1.3 cm.times.2.5 cm (1/2 in..times.1 in.) test specimen and
a 1000 g load. The test panels were stainless steel ("SS"). Time to
failure in minutes was recorded. If no failure was observed after
10,000 minutes, the test was stopped and a value of >10,000
minutes was recorded.
[0072] Static Shear Strength at 70.degree. C.: Evaluation of static
shear strength was performed as described in the ASTM International
standard, D3654, Procedure A, with a 1.3 cm.times.2.5 cm (1/2
in..times.1 in.) test specimen and a 500 g load. The test panels
were stainless steel ("SS"). Time to failure in minutes was
recorded. If no failure was observed after 10,000 minutes, the test
was stopped and a value of >10,000 minutes was recorded.
[0073] Materials
TABLE-US-00002 Material Abbreviation Function Manufacturer
Polyisobutylene B100 Unfunctionalized BASF (High MW 1000K Synthetic
g/mol) Rubber Polyisobutylene B268 Unfunctionalized Exxon (Medium
MW 500K Synthetic g/mol) Rubber Polyisobutylene G1000
Unfunctionalized BASF (Low MW 1000 Synthetic g/mol) Rubber Kerocom
.RTM. PIBA03 PIBA03 Functionalized BASF (~1000 g/mol of Synthetic
amine-terminated Rubber PIB) Acrylic copolymer IOA/AA of isooctyl
acrylate and acrylic acid Isobornyl acrylate IBA Foral 85 F85
Tackifier Eastman Eastotac 1310 E1310 Tackifier Eastman Crosslinker
The bisaziridine crosslinker utilized in the examples was prepared
according to 3M patent application No. 61/158,485, filed Mar. 9,
2009)
[0074] General Procedures. All reactions were performed in
round-bottomed flasks or glass jars/vials using commercial reagents
as received.
[0075] Adhesive compositions further comprising unfunctionalized
PIB were prepared according to the following procedure:
Kerocom.RTM. PIBA03 was added to a glass vial. Next, the isooctyl
acrylate/acrylic acid copolymer solution (e.g. 94:6 isooctyl
acrylate:acrylic acid or 90:10 isooctyl acrylate:acrylic acid in a
35% wt % ethyl acetate solution) was added, followed by adding
unfunctionalized PIB (in a 15 wt-% toluene solution) with tackfier
(e.g. E1310). Additional toluene was added to make the total solids
concentration equal 35 wt %. The concentration of each component in
the various formulations is illustrated in the tables. The
components were mixed well by shaking until the solution turned
translucent and the components were uniformly dispersed.
Immediately before coating, bisaziridine crosslinker (a 15 wt %
solution in toluene) was added and the formulation was again shaken
and mixed well. A hand spread was pulled onto a silicone release
liner (Silphan S36 M74A) using a 9 mill gap. The film was dried in
an oven at 70.degree. C. for 30 minutes. Next, the adhesive film
was allowed to cool to room temperature. The adhesive film was
0.0019'' thick. During the cohesion and adhesion strength testing,
2 mil (0.0020'') thick anodized aluminum was laminated on the PSA
tape as adhesive backing.
TABLE-US-00003 Stainless PP 90.degree. EPDM 90.degree. Steel
90.degree. Peel Peel IOA/AA Cross- Peel oz/in oz/in oz/in Example
B268 PIBA03 94:6 linker E1310 (N/dm) (N/dm) (N/dm) Control A 0.00
0.00 99.80 0.20 0.00 63 (69) 15 (16) 16 (18) Control B 49.95 0.00
49.95 0.10 0.00 49 (54) 17 (19) 16 (18) Ex. 1 29.97 19.98 49.95
0.10 0.00 36 (39) 27 (30) 20 (22) Ex. 2 27.25 18.17 45.41 0.09 9.08
49 (54) 42 (46) 26 (28)
[0076] With reference to FIGS. 1-2, the morphology of the
compositions of Control B and Example 1 were examined via
microscopy (10.times.). With reference to FIG. 2, the adhesive of
Example 1, comprising the functionalized PIB (e.g. PIBA03) bonded
to the acrylic polymer, exhibits a more uniformly dispersed phase
domain than FIG. 1, the adhesive of Control B lacking the
functionalized PIB. Without intending to be bound by theory, the
dispersion uniformity of the phase domain is surmised to closely
relate to the adhesion properties. For example, Control B exhibits
lower peel adhesion to low surface energy substrates such as PP and
EPDM. Such results are comparable to Control A, a pure Acrylic-PSA.
However, Examples 1 and 2, exhibit more homogeneous phases and
smaller phase domains. Hence, it can be concluded that the presence
of the functionalized PIB compatiblizes the two immiscible phases
of unfunctionalized high molecular weight (e.g. PIB) synthetic
rubber and the acrylic polymer. The resulting adhesive compositions
exhibit improved peel adhesion to low energy surface substrate.
TABLE-US-00004 Acrylic Stainless PP 90.degree. Copolymer Steel
90.degree. Peel Shear IOA/AA Cross- Peel oz/in oz/in @ R.T. Example
B100 PIBA03 (90:10) linker (N/dm) (N/dm) (min).sup.a Control C 60
40 0 0 25 (27) 24 (26) 192 Ex. 3 44.98 29.99 24.99 0.05 35 (38) 23
(25) 4891 Ex. 4 29.97 19.98 49.95 0.10 40 (44) 23 (25) >10000
Ex. 5 14.98 9.99 74.89 0.15 53 (58) 17 (19) 6721
[0077] With reference to FIGS. 3-5, the morphology of the
compositions of Examples 3-5 was also examined via microscopy
(20.times.). FIG. 3, the blend with 75 wt-% PIB (45 wt-%
unfunctionalized and 30 wt-% functionalized) exhibited a continuous
PIB domain as evident by the lighter areas in FIG. 3 and also dark
coalescences of acrylic copolymer domains. In FIG. 4, the blend
with 50 wt-% PIB the morphology changed to bicontinuous phases,
(i.e. a semi-interpenetrating network). As evident in FIG. 5, in
the blend having 25 wt-% PIB, the PIB domains became droplets
embedded in a continuous acrylic copolymer phase.
TABLE-US-00005 Stainless PP 90.degree. Steel 90.degree. Peel Shear
IOA/AA Cross- Peel oz/in oz/in @ R.T. Example B100 B268 PIBA03
90:10 linker E1310 (N/dm) (N/dm) (min).sup.a Ex. 6 24.98 0.00 24.98
49.95 0.10 0.00 68 (74) 31 (34) >10000 Ex. 7 0.00 29.97 19.98
49.95 0.10 0.00 63 (69) 32 (35) 5095 Ex. 8 27.25 0.00 18.17 45.41
0.09 9.08 143 (157) 48 (53) >10000 Ex. 9 23.06 0.00 15.37 38.43
0.08 23.06 90 (99) 62 (68) >10000 Ex. 10 27.25 0.00 18.17 45.41
0.09 9.08.sup.b 70 (77) 52 (57) >10000 IOA/AA Example B268
PIBA03 G1000 (94:6) Crosslinker E1310 F85 Ex. 11 33.33 11.11 22.22
0.00 0.00 33.33 0.00 Ex. 12 21.41 7.14 14.28 35.69 0.07 21.41 0.00
Ex. 13 18.74 6.25 12.49 31.23 0.06 18.74 12.49 Ex. 14 15.37 5.38
9.99 46.11 0.09 23.06 0.00 Ex. 15 13.32 4.66 8.66 39.97 0.08 19.98
13.32 Stainless PP 90.degree. HDPE 90.degree. EPDM 90.degree. Steel
90.degree. Peel Peel Peel Shear Shear Peel oz/in oz/in oz/in oz/in
@ R.T. @ Example (N/dm) (N/dm) (N/dm) (N/dm) (min).sup.a 70.degree.
C. (min).sup.a Ex. 11 47 (51) 53 (58) 36 (39) 33 (36) 13 0 Ex. 12
54 (59) 39 (43) 44 (48) 22 (24) >10000 634 Ex. 13 47 (51) 55
(60) 27 (30) 19 (21) >10000 1784 Ex. 14 70 (77) 54 (59) 42 (46)
37 (40) >10000 >10000 Ex. 15 40 (44) 49 (54) 50 (55) 33 (36)
>10000 >10000 .sup.aShear data were obtained using 0.5''
.times. 1.0'' strips on stainless steel with a 1000 g load, at room
temperature around 30.degree. C. .sup.band 10 wt-% F85
[0078] PIB-Acrylate Macromonomer. A 4 ounce amber bottle was
equipped with a plastic cap with an approximately 1/8'' hole.
Glissopal.RTM. SA (60.0 g) and a magnetic stir bar were added.
Next, 2-hydroxyethyl acrylate (6.00 mL, 6.07 g, 52.2 mmol) and
4-(dimethylamino)pyridine (0.0520 g, 0.426 mmol) were added. The
reaction was capped with the plastic cap and a piece of Teflon.RTM.
tubing was threaded through the hole and pushed into the bottom of
the reaction mixture. Air was passed through the tubing and bubbled
through the reaction mixture throughout the course of the reaction.
The reaction was placed in an oil bath and heated to 100.degree. C.
with stirring. After 3 days, the reaction was removed from the oil
bath and allowed to cool to room temperature. The acrylate product
was obtained as a pale yellow, very viscous liquid.
##STR00003##
[0079] General Procedure for the Preparation of Acrylate Copolymers
Using the PIB Macromonomer. PIB macromonomer (1.00 g) was added to
a 4 ounce amber bottle with Teflon.RTM.-wrapped threads. Hexane
(8.50 mL, 5.60 g) was added and the mixture was sonicated for 40
minutes to dissolve the macromonomer. Next, isooctyl acrylate (2.00
g), acrylic acid (0.150 g) and Vazo.RTM. 67 (0.010 g) were added
and the mixture was mixed until homogeneous. The reaction was
sparged with nitrogen for 7 minutes and then quickly sealed with a
Teflon.RTM.-lined plastic cap. The reaction was further sealed with
Teflon.RTM. tape and electrical tape. The reaction was placed in a
water bath/shaker at 65.degree. C. and gently agitated. After 24
hours, the reaction was removed from the water bath and was allowed
to cool to room temperature. The reaction mixture was then added to
methanol (100 mL) with stirring to precipitate the polymer product.
The hazy methanol solution was decanted and the viscous pale yellow
material was washed with methanol (3.times.5 mL). The precipitated
product was transferred to a 20 mL glass vial with hexane and was
then dried in vacuo to provide the polymer product (2.31 g, 73.1%)
as a clear, pale yellow rubbery solid.
##STR00004##
[0080] The acrylate-PIB copolymer was then utilized to prepare
adhesive compositions in the same manner as previously
described.
TABLE-US-00006 48% PIB- Peeling Peeling 48% IOA- on SS on PP Shear
IOA/AA Cross- 2% AA in/oz in/oz @ RT B100 PIBA03 90/10 linker
Copolymer (N/dm) (N/dm) (min) Ex. 16 27.25 18.17 45.41 0.09 9.08 18
(20) 46 (51) 92 Ex. 17 40.89 27.26 22.72 0.05 9.09 38 (42) 23 (25)
662 Ex. 18 13.62 9.08 68.09 0.14 9.08 43 (47) 26 (29) 27 32% PIB-
Peeling Peeling 63% IOA- on SS on PP Shear IOA/AA Cross- 5% AA
in/oz in/oz @ RT B100 PIBA03 90/10 linker Copolymer (N/dm) (N/dm)
(min) Ex. 19 27.25 18.17 45.41 0.09 9.08 73 (80) 40 (44) 6681 Ex.
20 13.62 9.08 68.09 0.14 9.08 70 (77) 48 (53) 1208 63% PIB- Peeling
Peeling 32% IOA- on SS on PP Shear IOA/AA Cross- 5% AA in/oz in/oz
@ RT B268 PIBA03 94/6 linker Copolymer (N/dm) (N/dm) (min) Ex. 21
32.70 21.80 36.34 0.07 9.08 44 (48) 39 (43) 2193 Ex. 22 27.25 18.17
45.41 0.09 9.08 37 (41) 33 (36) 2396 Ex. 23 21.79 14.53 54.49 0.11
9.08 46 (51) 26 (29) 3304 47.5% PIB- Peeling Peeling 47.5% IOA- on
SS on PP Shear IOA/AA Cross- 5% AA in/oz in/oz @ RT B268 PIBA03
94/6 linker Copolymer (N/dm) (N/dm) (min) Ex. 24 32.70 21.80 36.34
0.07 9.08 30 (33) 22 (24) 3912 Ex. 25 27.25 18.17 45.41 0.09 9.08
30 (33) 18 (20) 3191 Ex. 26 21.79 14.53 54.49 0.11 9.08 42 (46) 39
(43) 3341
* * * * *